It might be available dodgily on torrent... but my dodgy one doesn't work :/
Have you tried applying the latest** free Garmin update to it? You can firewall it to be sure, but ISTR it doesn't register online anyway.
** Or the next-but-one latest, is much better.
The problem with the method whereby you just copy a gmapsupp.img into a directory called /Garmin/ - is that there can only be one file/directory of that name. What Mapsource can do is combine tiles from different sources, into a single gmapsupp.img, this being the only filename the GPS can use. (I think Colorados and Oregons are better here - they can have multiple mapsets on their cards.)
Having said that, I lied earlier - MapSet ToolKit works like a charm, to get OSM into Mapsource - but I haven't yet succeeded in using Mapsource to load a combined map (metroguide/worldmap/OSM) into the Garmin - it
appears to go OK, and the OSM map tiles are visible on the GPS screen, and they are registered and named correctly in the GPS setup page - but on zooming in there's no mapping visible. Switch them off and the other maps (metroguide or worldmap) work OK.
[edit] - now got it working, 'mixed' maps on GPS - not sure what I did different ...
Incidentally OSM looks quite a bit better than Worldmap in S.India, which is of particular interest to me just now. Its not so much that its more detailed, but the detail there is is much more accurately placed (Worldmap is really pretty awful). Unlike the UK where I think its not quite so spot-on accurate at the junctions as Metroguide (and it has a lot less road detail even though some of the cycleroute stuff makes valuable additions).